Knowing how to capture an image is not difficult. However, mastering photography has a steep learning curve. Creation of a good image involves many skills from preparing to capture the image to post-processing. It is almost impossible to master such skills without years of study and practice.
In order to encourage more people to take up photography and to assist beginner/amateur photographers to capture good images, many methods, such as auto-focus and auto-exposure, have been developed to improve image quality in every step of the image creation process.
Many methods exist for improving image quality by detecting and removing image artefacts, such as noise, blocking artefacts and motion blur. Such artefacts significantly degrade image quality. However, artefacts are not the most important deterministic factor for image quality. No matter how sharp or noise-free an image is, the image cannot be a good image if a subject/theme of the image is not well presented.